Faculty Engineering and Technology

Mechanical Engineering
Department

Course Mechanical Engineering

Title Steam Nozzle Practical

Student Name

Student Number

Date of Practical 26 April 2023

Date of submission 7 May 2023

Table of Contents
Introduction.........................................................................................................................................2
Aim...................................................................................................................................................2
Schematic diagram..........................................................................................................................2
Special Techniques...........................................................................................................................2
Observation..........................................................................................................................................2
General constants............................................................................................................................2
Data...................................................................................................................................................3
Processing.............................................................................................................................................3
Sample processing............................................................................................................................3
Tables................................................................................................................................................7
INTERMEDIATE VALUES..........................................................................................................7
ESSENTIAL TABLE.....................................................................................................................7
Graph...................................................................................................................................................8
Table of Graphs...............................................................................................................................8
Conclusion............................................................................................................................................8
Observation......................................................................................................................................8
Processed values...............................................................................................................................8
Graph trend.....................................................................................................................................8
Recommendation.............................................................................................................................8
Introduction
Aim
 The experiment aims to investigate the performance of a steam nozzle in a steam turbine
system.
 The ideal and experimental values of steam enthalpy at nozzle entry will be compared to
determine nozzle efficiency.
 The effect of changing the condenser pressure on various parameters such as steam mass
flow rate, dryness fraction, and nozzle-exit speed will be analysed.
 The experiment aims to quantify the extent of changes in these parameters resulting from
varying the condenser pressure.
 The experiment will provide insight into steam turbine system performance and help to
optimize efficiency.

Schematic diagram

Special Techniques
 A flow meter was used to measure cooling water mass flow rate with precision.
 Laboratory conditions were free of drafts to eliminate interference.
 All measuring instruments were accurately calibrated before the experiment.
 To avoid changes in turbine inlet pressure, the throttle valve was carefully and slowly
opened.
 To prevent parallax errors, condensate readings were taken by focusing on a parallel
line of sight with the 200 cm3 mark.
Observation
General constants
1. Environmental:
 Room temperature, TR = 22 oC
 Atmospheric Pressure, PATM = 87 kPa
2. Setup:
 Nozzle diameter, DN = 3 mm

Data
COLUMN 1 2 3 4 5
TURBINE EXIT/CONDENSER PRESSURE, P2 -10 -20 -30 -40 -50
TURBINE INLET TEMPERARTURE (T1) 143 144.7 143.6 143 143.3
CONDENSATE TEMPERATURE (T3) 32.5 30.4 31.9 33.4 33.4
COOLING WATER INLET TEMPERATURE (Tinlet) 20.8 20.8 20.9 20.9 20.9
COOLING WATER OUTLET TEMPERATURE 45.5 45.7 46.8 45.9 47.8

TIME FOR 200 𝑚^3 CONDENSATE, t

(Toutlet)
03:18 03:10 03:21 03:14 03:14
COOLING WATER FLOW RATE, Mw (g/s) 20 20 20 20 20

Processing
Sample processing
P1abs = P1 (gage) + Patm
P1abs = 300 kPa + 87 kPa
P1abs = 387 kPa
Therefore, conditions at inlet to the nozzle are: P1abs = 387 kPa, T1 = 143oC
The values indicate superheated steam at nozzle inlet, so superheated steam tables with
interpolations was used
P1abs is found between 300 kPa and 400 kPa on the superheated steam table therefore, to
calculate the value of h1, we interpolate between h(300) at 142.5oC and h(400) at 142.5oC.

For h(300) at 143oC, we extrapolate with h(300) at 150 oC and h(300) at 200 oC:
h(300) at 200 oC = 2866 kJ/kg h(300) at 150 oC = 2762 kJ/kg:
(150−143)(2866−2762)
h(300@143 oC) = 2762 -
200−150
h(300@141.2 oC) = 2747.44kJ/kg
For h(400) at 143oC, we extrapolate with h(400) at 150 oC and h(400) at 200 oC:
h(400) at 200 oC = 2862 kJ/kg h(400) at 150 oC = 2753 kJ/kg:
(150−143)(2862−2753)
h(400@141.2 oC) = 2753 -
200−150
h(400@141.2 oC) = 2737.74kJ/kg

For h1 at P1abs = 387 kPa, we interpolate between h(300) at 143oC and h(400) at 143oC:
(387−300)×(2737.74−2747.44 )
h1 = 2747.44 +
400−300
h1 = 2739.001kJ/kg

P2abs = P2 (gage) + Patm

P2abs = -10 kPa + 87 kPa
P2abs = 77 kPa

The value of P2abs is found between the limits 75 kPa and 80 kPa on the wet vapour steam
table therefore, to calculate the values of T2sat@P2abs, hf@T2sat, hfg@T2sat and vg@T2sat, we interpolate
between T(@75) & T(@80), hf(@75) & hf(@80), hfg(@75) & hfg(@80), and vg(@75) & vg(@80) :

T(@75) = 98.1 oC
T(@80) = 93.5 oC
(77−75)×(93.5−98.1)
T2sat@P2abs = 98.1 +
80−75
T2sat@P2abs = 96.26 oC

hf(@75) = 385 kJ/kg

hf(@80) = 392 kJ/kg
(77−75)×(392−385)
hf@T2sat = 385 +
80−75
hf@T2sat = 388 kJ/kg
hfg(@75) = 2279 kJ/kg
hfg@80) = 2274 kJ/kg
(77−75)×(2274−2279)
hfg@T2sat = 2279 +
80−75
hfg@T2sat = 2277 kJ/kg

vg(@75) = 2.217 m3/kg

vg(@80) = 2.087 m3/kg
(77−75)×(2.087−2.217)
vg@T2sat = 2.217 +
80−75
vg@T2sat = 2.1650 m3/kg
T3 = 32.5 oC
T3 is in the saturated water region, hence interpolations are made from the steam tables for h 3
= hf@T3:
hf(@31) = 130 kJ/kg
hf(@32.9) = 138 kJ/kg
(32.5−31)×(138−130)
hf@T3 = 130+
32.9−31
hf@T3 = 136.3158 kJ/kg

vf(@30) = 0.0010046 m3/kg

vf(@35) = 0.001006 m3/kg
(32.5−30)×(0.001006−0.0010046)
vf@T3 = 0.0010046 +
35−30
vf@T3 = 0.0010053 m3/kg

For the mass flow rate of the condensate:

t = 3:18 = (3×60) + 18 = 198 s
−6
200× 10 1
ṁs = ×
vf 3 t
 −6
200 ×10
∗1
⇒ ṁs = 0.0010053 = 1.005×10-3 kg/s
198

For the specific heat capacity of the cooling water:

T wi +T wo
Tw(av) = = 33.15 oC
2
⇒ Tw(av) = 33.15 oC

cpf (@30) = 4.179 kJ/kgK

cpf (@35) = 4.178 kJ/kgK
(33.15−30)×(4.178−4.179)
cw(av) = 4.179 +
35−30
cw(av) = 4.1784 kJ/kgK

h3 = 136 kJ/kg ṁw = 0.02 kg/s TWO = 45.5 oC TWI = 20.8 oC

ṁs ( h2−h3 )= ṁw c w /av ( T wo−T wi )

ṁw c w /av ( T wo −T wi )
h2 = +h3
ṁs
h2 =2190.62kJ/kg

hf@T2sat = 388 kJ/kg

hfg@T2sat = 2277 kJ/kg
h2 =hf @T 2 sat + x2 ×h fg @T 2 sat

h2−h f @ T 2 sat 2190.62−388

x 2= = =0.79
h fg @T 2 sat 2277

vg@T2sat = 2.1650 m3/kg

v 2=x 2 × v g 2 @ T 2 sat
v 2=x 2 × v g 2 @ T 2 sat =0.79× 2.1650

v 2=1.7141m3/kg

ṁs = 1.005×10-3 kg/s

v2 = 1.7141 m3/kg
DN = 3 mm = 0.003 m
ṁs v 2= A N C 2

π 2
ṁ s v 2= D C
4 N 2
4 × ṁs v 2 −3
4 ×1.005 ×10 × 1.7141
C 2= 2
= 2
π × DN π ×0.003
C 2=243.6598m/s

h2 =2190.62kJ/kg
2
C
h1 s −h2=
2
2 2
C 243.6598 3
h1 s = + h2 = +2190.62 ×10
2 2
h1 s =2220.30 kJ/kg

h1 = 2739.001 kJ/kg
∆ h=h1 −h1 s=2739.001−2220.30

⇒ ∆ h=518.70 kJ/kg

Tables
INTERMEDIATE VALUES

P2 P2abs T2sat hf2 hfg2 vg2 T3 h3 Tw/av cpf

(kPa) (kPa) (oC) (kJ/kg) (kJ/kg) (m3/kg) (oC) (kJ/kg) (oC) (kJ/kgK)
-10 77.0 96.26 388 2277 2.1650 32.5 136 33.15 4.1784
-20 67.0 88.80 372 2286 2.4670 30.4 127 33.25 4.1784
-30 57.0 84.62 355 2297 2.8712 31.9 134 33.85 4.1782
-40 47.0 79.78 334 2309 3.4416 33.4 140 33.4 4.1783
 -50 37.0 74.05 310 2324 4.2990 33.4 140 34.35 4.1781

ESSENTIAL TABLE
P2abs ṁs h2 x2 C T1 h1 h1s ∆h
(kPa) (kg/s) (kJ/kg) (m/s) (oC) (kJ/kg) (kJ/kg) (kJ/kg)
77.0 0.001005 2190.62 0.79 243.6598 143.0 2739.001 2220.30 518.70
67.0 0.001048 2113.39 0.76 278.5108 144.7 2742.685 2152.18 590.51
57.0 0.000990 2320.10 0.86 344.0751 143.6 2740.301 2379.29 361.01
47.0 0.001025 2177.80 0.80 398.4819 143.0 2739.001 2257.19 481.81
37.0 0.001025 2332.56 0.87 542.6562 143.3 2739.651 2479.80 259.85

Graph
Table of Graphs

P2 ṁs ×10
−3
x2 C ∆h
(kPa) (kg/s) (m/s) (kJ/kg)
-10 1.005 0.79 243.6598 518.70
-20 1.048 0.76 278.5108 590.51
-30 0.990 0.86 344.0751 361.01
-40 1.025 0.80 398.4819 481.81
-50 1.025 0.87 542.6562 259.85

Conclusion
Observation
During the experiment, it was observed that the temperature of the cooling water consistently
exceeded the inlet temperature at the outlet. This aligns with the proposed heat balance
equation. Additionally, the time required to collect the condensate increased as the condenser
inlet pressure decreased, indicating an inverse relationship with the steam mass flow rate.
However, the accuracy of the observations was somewhat impacted by a minor malfunction
in the experimental apparatus.

Processed values
Results were accurate up to the second decimal, except for fully decimal fractions which had
discretionary accuracy. All computations used SI units and simplified relevant exponents
beforehand.
 Graph trend
The steam mass flow rate, dryness fraction, and enthalpy difference exhibited fluctuations,
resulting in waveform graphs.

Recommendation
 Maintenance on the apparatus could prevent inaccurate readings
 The recordings should be done carefully